Not applicable.
The present invention generally relates to the field of fluid systems and, more particularly to joints within fluid system ducting which accommodate relative movement between different portions of the fluid system.
In certain launch vehicles, some trajectory control of the launch vehicle in flight is provided through the use of steerable rocket engines. Such steerability is generally achieved by interconnecting actuators (e.g., hydraulic or electric) to a gimballed rocket engine. To accommodate such steerability, typical fuel lines extending between the steerable rocket engines and the fuel or propellant tanks (e.g., containing liquid oxygen or hydrogen) utilize flexible ducts. Such existing flex ducts consist of multiple flex hoses fabricated from stainless steel (e.g., for some launch vehicles, at least three flex hoses) which can be stretched, compressed or angulated in an accordion-like fashion to provide the steerability required. However, use of such flex ducts can be expensive, and the layout of such flex ducts is complex due to the length and flex requirements of the flex duct (e.g., six feet in length). In addition, such flex ducts are heavy (e.g., weighing about eighteen pounds each), and typically require a support structure (e.g., one or more dampers) to interconnect the flex duct to the bulkhead of the launch vehicle (e.g., an upper stage of the launch vehicle). Furthermore, when pressurized, such flex ducts may impart unacceptably high loads on the interfaces between the flex duct and rocket engine (e.g., flange interconnected to a turbopump of the rocket engine) because of the flex duct""s propensity to stretch when pressurized, which can result in unacceptable engineering interface deflections in the turbopump.
As such, it is an object of the present invention to provide a duct system for fluidly interconnecting first and second systems or devices, the duct system being adapted to allow at least one of angular and linear motion of the first system or device relative to the second system or device.
It is another object of the present invention to provide a propellant duct system which allows an engine in fluid communication therewith to be steered.
It is another object of the present invention to provide a propellant duct system which allows a rocket engine gimbal assembly to move linearly and angularly relative to the sump or propellant gimbal assembly.
It is yet another object of the present invention to provide a propellant duct system which accommodates about four degrees of angular motion and/or linear motion of a rocket engine relative to a fuel or propellant tank.
It is still another object of the present invention to provide a propellant duct system which is simple, lightweight, dynamically sealed and uncompensated, the propellant duct system extending between a steerable rocket engine and a propellant or fuel tank.
One propellant duct system in accordance with principles of the present invention achieves one or more of these objectives by providing a system which is dual gimballed, uncompensated, dynamically sealed and lightweight. In particular, this particular propellant duct system of the present invention accommodates rocket engine gimbal motion through the use of at least a first gimbal joint which allows rotational or angular rocket engine motion relative to a propellant tank in fluid communication therewith and a dynamic, redundantly sealed slip joint which allows linear rocket engine motion relative to the propellant tank. Through the use of such components, a flexible fuel line of reduced length (e.g., 2 feet, as opposed to 6 feet in current flex ducts) and weight (e.g., nine pounds, as opposed to 18 pounds in current flex ducts) is achieved. In addition, the propellant duct system of the present invention does not require the use of dampers to support the same.
A first aspect of the present invention is a fluid system which includes a fluid duct assembly which may be used to fluidly interconnect certain fluid system components (e.g., a rocket engine and a rocket fuel tank). This fluid duct assembly includes first and second duct sections. These first and second duct sections are interconnected by a first slip joint which allows the first duct section to effectively slide relative to the second duct to section (e.g., relative linear motion). Other joints exist in the fluid duct assembly. In this regard, a first gimbal joint is interconnected with the first duct section and a second gimbal joint is interconnected with the second duct section. Both the first and second gimbal joints accommodate certain types relative movement of their corresponding first and second duct sections (e.g., angular or rotational motion). In one embodiment, the first slip joint is disposed somewhere between the first and second gimbal joints.
Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. Both the first and second duct sections may include what may be characterized as first and second ends which are longitudinally spaced in that the distance between these ends may define a length dimension for the respective first and second duct section. The first gimbal joint may be interconnected with the first end of the first duct section and the second gimbal joint may be interconnected with the first end of the second duct section. This arrangement allows the second end of the first duct section to extend through the second end of the second duct section and at least partially within the second duct section, or vice versa, for instance in a concentric relation. In any case, the first slip joint could then be disposed within an annular space which may exist between concentric portions of the first and second duct sections or those portions of the first and second duct sections which define a telescope-like arrangement.
Components of the first slip joint may include a pair of longitudinally-spaced bushings and at least one annular seal which is disposed at an intermediate location between these pair of longitudinally-spaced bushings. Preferably all annular seals are disposed somewhere between these pair of longitudinally-spaced bushings. Multiple functions may be provided by these bushings. Initially, the bushings may be incorporated in the first slip joint so as to inhibit contact between the first and second duct sections. Moreover, these bushings may be incorporated in the first slip joint so as to carry a load which is exerted on the duct assembly and applied in some manner to the first slip joint. Consider the case where the second end of the first duct section extends through the second end of the second duct section to concentrically dispose the first duct section relative to the second duct section. An outer wall of the first duct section may include a plurality of annular grooves which are longitudinally-spaced. Each annular seal may be disposed in its own annular groove on the outer wall of the first duct section and may be biased toward and in engagement with a portion of an inner wall of the second duct section and a portion of the outer wall of the first duct section (which includes the groove) by its own biasing member (e.g., a spring which is disposed within a generally u-shaped section of its corresponding annular seal). Annular grooves may be provided for each of the noted bushings as well. Each of the annular seals may be disposed at some longitudinal position between the pair of longitudinally-spaced bushings. Having the bushings be xe2x80x9cthickerxe2x80x9d than their corresponding annular groove results in these bushings extending beyond the outer wall of the first duct section so as to provide one or more of the above-noted functions.
The duct assembly of the subject first aspect is particularly suited for fluidly interconnecting a rocket engine and a rocket fuel tank. The arrangement presented by the subject first aspect allows an appropriate rocket fuel (e.g., a liquid propellant) to be directed from the fuel tank to the rocket engine. Moreover, the arrangement provided by the subject first aspect allows the length of the duct assembly which interconnects this rocket engine and fuel tank to be significantly reduced, and in one embodiment the length of the duct assembly may be about 2 feet. This reduced length provides the benefit of reducing material costs, reducing the weight of the entire fluid system and thereby a space travel vessel which includes the same.
A second aspect of the present invention is a fluid system which includes a fluid duct assembly which may be used to fluidly interconnect certain fluid system components (e.g., a rocket engine and a rocket fuel tank). This fluid duct assembly includes first and second duct sections. These first and second duct sections are interconnected by a first slip joint which allows the first duct section to effectively slide relative to the second duct section (e.g., relative linear motion). Components of the first slip joint include a pair of longitudinally-spaced bushings and at least one annular seal which is disposed at an intermediate location between these pair of longitudinally-spaced bushings. All annular seals of the first slip joint utilized by the subject second aspect of the present invention are preferably disposed somewhere between its pair of longitudinally-spaced bushings.
Various refinements exist of the features noted in relation to the first aspect of the present invention. Further features may also be incorporated in the first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. Both the first and second duct sections may include what may be characterized as first and second ends which are longitudinally spaced in that the distance between these ends may define a length dimension for the respective first and second duct section. The second end of the first duct section may extend through the second end of the second duct section and at least partially within the second duct section, or vice versa, for instance in a concentric relation. In either case, the first slip joint may then be disposed within an annular space which may exist between the concentric portions of the first and second duct sections or between those portions of the first and second duct sections which define a telescope-like arrangement.
Multiple functions may be provided by the bushings in the first slip joint utilized by the subject second aspect of the present invention. Initially, the bushings may be incorporated in the first slip joint so as to inhibit contact between the first and second duct sections. Moreover, these bushings may be incorporated in the first slip joint so as to carry a load which is exerted on the duct assembly and applied in some manner to the first slip joint. Consider the case where one end of the first duct section extends through one end of the second duct section to concentrically dispose the first duct section relative to the second duct section or so as to define a telescope-like arrangement. An outer wall of the first duct section may include a plurality of annular grooves which are longitudinally-spaced. Each annular seal may be disposed in its own annular groove on the outer wall of the first duct section and may be biased toward and in engagement with a portion of an inner wall of the second duct section and a portion of the outer wall of the first duct section (which includes the groove) by its own biasing member (e.g., a spring which is disposed within a generally u-shaped section of its corresponding annular seal). Annular grooves may be provided for each of the noted bushings as well. Each of the annular seals may be disposed at some longitudinal position between the pair of longitudinally-spaced bushings. Having the bushings be xe2x80x9cthickerxe2x80x9d than their corresponding annular groove results in these bushings extending beyond the outer wall of the first duct section so as to provide one or more of the above-noted functions.
Other joints may exist in the fluid duct assembly utilized by the subject second aspect of the present invention. In this regard, a first gimbal joint may be interconnected with the first duct section and a second gimbal joint may be interconnected with the second duct section. Both the first and second gimbal joints accommodate certain types relative movement of their corresponding first and second duct section (e.g., angular or rotational motion). In one embodiment, the first slip joint is disposed somewhere between the first and second gimbal joints. Typically these first and second gimbal joints will be disposed on ends of their respective first and second duct section which is disposed beyond the first slip joint.